The management of keractoconus
Keratoconus has always been considered a dark and mysterious disease. Several studies have been carried out to understand its etiology and its progression, leading to evolutions in its knowledge, but still leaving much to be discovered. In 2013 Patel DV stated: "Keratoconus remains an enigmatic disease in terms of heredity, prevention, associated risk factors, progression, treatment and underlying pathophysiology".
Some studies recently, after a review of contemporary genetic analyzes, have pointed out that keratoconus could have two possible etiologies, endogenous (genetic factors) and exogenous (environmental factors). A recent epidemiological study, conducted in the Netherlands in 2017, reported an increase in the prevalence of keratoconus in the general population (1/375) compared to what was found in previous studies conducted in 1986. This indicates that keratoconus is more common than has been indicated. This increase is about 5 to 10 times and could be the result of the greater availability of modern techniques for the diagnosis of keratoconus. Another possible explanation could be that of the higher incidence of allergic reactions. In fact, keratoconus seems to manifest itself more in people with allergies. Prevalence also depends on the gender and the geographical place where people live, for example the male gender and the population in the Asian continent are those most affected by this corneal disease.
The rubbing of the eyes has long been attributed to keratoconus as a consequence of an atopic disease which also contributes to its advancement up to an acute hydrops. So this association seems to be indirect. According to these claims, patients who do not suffer from allergies should have a less pronounced keratoconus than atopic ones. Furthermore, subjects suffering from both keratoconus and allergies should have the same rubbing movement of the eyes as exclusively allergic patients. But analyzing these aspects, things don't seem that way. In fact, according to Carlson, not all eye rubs are similar. Allergic patients rub their eyes in a linear way in response to an itch stimulus and are aware of this stimulus-response act. On the other hand, patients with keratoconus have a different attitude. Even those who are affected by allergies, rub their eyes not only for the itching but also for the burning or to get a relief, but especially for a better vision. Not only the symptoms that lead to rubbing are different, but also the frequency, duration, mode, pressure exerted and the movement of the rubbing.
Allergic patients initially use a flat surface to rub their eyes, such as the palm of the hand and the back of the hand, making a horizontal movement on the eyelid, back and forth, causing an eyelid movement and therefore exerting greater pressure on the eyelid and minimum on the cornea. This rubbing is often followed by another with the tip of the index finger on the caruncle, which then becomes a circular and more intense movement. If these patients had long nails, they would rub on the caruncle with the knuckle of the index finger. The total time of rubbing the eyes in allergic subjects lasts on average 15 seconds. These patients are very aware of the rubbing and have the final feeling of the mission accomplished to satisfy a need, which they prefer not to repeat.
Keratoconic patients, although they have an allergy, tend to rub their eyes in a different way. They use two ways, or with the knuckle of the index finger, or with two fingers, index and middle fingers, with a circular and intense movement, exerting all the pressure on the cornea. The frequency and duration of rubbing are greater than in atopic patients, which ranges from 10 to 180 seconds, sometimes even 300 seconds, several times a day. Instead, these patients are not aware of this repetitive gesture that becomes a habit. In the end, they have a feeling of great relief, almost entranced and would like to repeat it continuously.
Also according to Carlson, the position taken during sleep also contributes to the progression of keratoconus. He argues that, following his observations and anamnesis with patients, subjects with asymmetrical keratoconus tend to sleep on the side of the eye where the keratoconus is more advanced or in a phase of greater progression. Some patients sleep with their faces over their bent arm, exerting pressure directly on the eye. Others prefer to put their hand under the pillow by pressing on the eye. These positions could cause continuous pressure, for a long period, which could contribute to the progression of ectasia. In addition, the presence of the cushion that presses under the eye could cause the eyelid to overheat, limiting the space for heat dispersion.
The most common correction of the corneal irregularity caused by keratoconus is the contact lens. Depending on the keratoconus stage, the most suitable contact lens, technique and / or geometry for the specific case is chosen. These include the soft, hybrid, piggyback, corneal and scleral rigid lens. Previous studies have indicated that 10% -20% of patients with keratoconus need keratoplasty. But the advent of new materials and geometries of corneal but especially scleral rigid contact lenses have reduced the need for a keratoconus transplant.